A strike by bus drivers here in Brazil's second city left tens of thousands of commuters stranded on Friday.

Unions representing the drivers called a 24-hour strike after failing to reach agreement with the transit companies on a new contract.

The workers want an increase of 15 percent, but owners are offering a pay hike of only 8 percent.

Less than 10 percent of Rio's bus fleet was on the streets Friday morning, while some transit companies said strikers hurled rocks at drivers who tried to take their units out from depots in the west-side neighborhoods of Santa Cruz and Campo Grande.

Growing crowds of people were seen waiting for hours at bus stops, while shops around Copacabana beach opened late as employees struggled to get to work.

"I'm waiting 40 minutes for a bus to go to a medical appointment," a middle-aged man told fellow commuters as he tried in vain to flag down a taxi.

The impact of the bus strike was amplified by the shutdown of parts of the city's metro system amid an expansion prompted by Rio de Janeiro's role as host of the 2016 Summer Olympics.

Brazilian President Dilma Rousseff was scheduled to be in Rio on Friday for events linked to the 448th anniversary of the city's founding. EFE